Space and astronomy news
Article updated at 3:40 pm CST, 1/24/20.
NASA’s Curiosity Mars rover experienced a technical glitch last week, causing it to temporarily lose its sense of direction and freeze in its tracks. But the talented rover repair team back on Earth enabled a fix, and Curiosity is now back in action.
Continue reading “A Glitch Caused Curiosity to Freeze in Place. But It’s Better Now”
Clay is a big deal on Mars because it often forms in contact with water. Find clay, and you’ve usually found evidence of water. And the nature, history, and current water budget on Mars are all important to understanding that planet, and if it ever supported life.
Continue reading “Curiosity has Found the Mother Lode of Clay on the Surface of Mars”
It’s hard to believe that MSL Curiosity has been on Mars for almost seven years. But it has, and during that time, the rover has explored Gale Crater and Mt. Sharp, the central peak inside the crater. And while it has used its drill multiple times to take rock samples, this is the first sample it’s gathered from the so-called ‘clay unit.’
Continue reading “Curiosity has Finally Sampled a Clay-Rich Region on Mars”
Some very clever people have figured out how to use MSL Curiosity’s navigation sensors to measure the gravity of a Martian mountain. What they’ve found contradicts previous thinking about Aeolis Mons, aka Mt. Sharp. Aeolis Mons is a mountain in the center of Gale Crater, Curiosity’s landing site in 2012.
Gale Crater is a huge impact crater that’s 154 km (96 mi) in diameter and about 3.5 billion years old. In the center is Aeolis Mons, a mountain about 5.5 km (18,000 ft) high. Over an approximately 2 billion year period, sediments were deposited either by water, wind, or both, creating the mountain. Subsequent erosion reduced the mountain to its current form.
Now a new paper published in Science, based on gravity measurements from Curiosity, shows that Aeolis Mons’ bedrock layers are not as dense as once thought.
Continue reading “NASA used Curiosity’s Sensors to Measure the Gravity of a Mountain on Mars”
5 years after a heart throbbing Martian touchdown, Curiosity is climbing Vera Rubin Ridge in search of “aqueous minerals” and “clays” for clues to possible past life while capturing “truly breathtaking” vistas of humongous Mount Sharp – her primary destination – and the stark eroded rim of the Gale Crater landing zone from ever higher elevations, NASA scientists tell Universe Today in a new mission update.
“Curiosity is doing well, over five years into the mission,” Michael Meyer, NASA Lead Scientist, Mars Exploration Program, NASA Headquarters told Universe Today in an interview.
“A key finding is the discovery of an extended period of habitability on ancient Mars.”
The car-sized rover soft landed on Mars inside Gale Crater on August 6, 2012 using the ingenious and never before tried “sky crane” system.
A rare glimpse of Curiosity’s arm and turret mounted skyward pointing drill is illustrated with our lead mosaic from Sol 1833 of the robot’s life on Mars – showing a panoramic view around the alien terrain from her current location in October 2017 while actively at work analyzing soil samples.
“Your mosaic is absolutely gorgeous!’ Jim Green, NASA Director Planetary Science Division, NASA Headquarters, Washington D.C., told Universe Today
“We are at such a height on Mt Sharp to see the rim of Gale Crater and the top of the mountain. Truly breathtaking.”
The rover has ascended more than 300 meters in elevation over the past 5 years of exploration and discovery from the crater floor to the mountain ridge. She is driving to the top of Vera Rubin Ridge at this moment and always on the lookout for research worthy targets of opportunity.
Additionally, the Sol 1833 Vera Rubin Ridge mosaic, stitched by the imaging team of Ken Kremer and Marco Di Lorenzo, shows portions of the trek ahead to the priceless scientific bounty of aqueous mineral signatures detected by spectrometers years earlier from orbit by NASA’s fleet of Red Planet orbiters.
“Curiosity is on Vera Rubin Ridge (aka Hematite Ridge) – it is the first aqueous mineral signature that we have seen from space, a driver for selecting Gale Crater,” NASA HQ Mars Lead Scientist Meyer elaborated.
“And now we have access to it.”
The Sol 1833 photomosaic illustrates Curiosity maneuvering her 7 foot long (2 meter) robotic arm during a period when she was processing and delivering a sample of the “Ogunquit Beach” for drop off to the inlet of the CheMin instrument earlier in October. The “Ogunquit Beach” sample is dune material that was collected at Bagnold Dune II this past spring.
The sample drop is significant because the drill has not been operational for some time.
“Ogunquit Beach” sediment materials were successfully delivered to the CheMin and SAM instruments over the following sols and multiple analyses are in progress.
To date three CheMin integrations of “Ogunquit Beach” have been completed. Each one brings the mineralogy into sharper focus.
Credit: NASA/JPL-Caltech/MSSS
What’s the status of the rover health at 5 years, the wheels and the drill?
“All the instruments are doing great and the wheels are holding up,” Meyer explained.
“When 3 grousers break, 60% life has been used – this has not happened yet and they are being periodically monitored. The one exception is the drill feed (see detailed update below).”
NASA’s 1 ton Curiosity Mars Science Laboratory (MSL) rover is now closer than ever to the mineral signatures that were the key reason why Mount Sharp was chosen as the robots landing site years ago by the scientists leading the unprecedented mission.
Along the way from the ‘Bradbury Landing’ zone to Mount Sharp, six wheeled Curiosity has often been climbing. To date she has gained over 313 meters (1027 feet) in elevation – from minus 4490 meters to minus 4177 meters today, Oct. 19, 2017, said Meyer.
The low point was inside Yellowknife Bay at approx. minus 4521 meters.
VRR alone stands about 20 stories tall and gains Curiosity approx. 65 meters (213 feet) of elevation to the top of the ridge. Overall the VRR traverse is estimated by NASA to take drives totaling more than a third of a mile (570 m).
“Vera Rubin Ridge” or VRR is also called “Hematite Ridge.” It’s a narrow and winding ridge located on the northwestern flank of Mount Sharp. It was informally named earlier this year in honor of pioneering astrophysicist Vera Rubin.
The intrepid robot reached the base of the ridge in early September.
The ridge possesses steep cliffs exposing stratifications of large vertical sedimentary rock layers and fracture filling mineral deposits, including the iron-oxide mineral hematite, with extensive bright veins.
VRR resists erosion better than the less-steep portions of the mountain below and above it, say mission scientists.
What’s ahead for Curiosity in the coming weeks and months exploring VRR before moving onward and upwards to higher elevation?
“Over the next several months, Curiosity will explore Vera Rubin Ridge,” Meyer replied.
“This will be a big opportunity to ground-truth orbital observations. Of interest, so far, the hematite of VRR does not look that different from what we have been seeing all along the Murray formation. So, big question is why?”
“The view from VRR also provides better access to what’s ahead in exploring the next aqueous mineral feature – the clay, or phyllosilicates, which can be indicators of specific environments, putting constraints on variables such as pH and temperature,” Meyer explained.
The clay minerals or phyllosilicates form in more neutral water, and are thus extremely scientifically interesting since pH neutral water is more conducive to the origin and evolution of Martian microbial life forms, if they ever existed.
How far away are the clays ahead and when might Curiosity reach them?
“As the crow flies, the clays are about 0.5 km,” Meyer replied. “However, the actual odometer distance and whether the clays are where we think they are – area vs. a particular location – can add a fair degree of variability.”
The clay rich area is located beyond the ridge.
Over the past few months Curiosity make rapid progress towards the hematite-bearing location of Vera Rubin Ridge after conducting in-depth exploration of the Bagnold Dunes earlier this year.
“Vera Rubin Ridge is a high-standing unit that runs parallel to and along the eastern side of the Bagnold Dunes,” said Mark Salvatore, an MSL Participating Scientist and a faculty member at Northern Arizona University, in a mission update.
“From orbit, Vera Rubin Ridge has been shown to exhibit signatures of hematite, an oxidized iron phase whose presence can help us to better understand the environmental conditions present when this mineral assemblage formed.”
Curiosity is using the science instruments on the mast, deck and robotic arm turret to gather detailed research measurements with the cameras and spectrometers. The pair of miniaturized chemistry lab instruments inside the belly – CheMin and SAM – are used to analyze the chemical and elemental composition of pulverized rock and soil gathered by drilling and scooping selected targets during the traverse.
A key instrument is the drill which has not been operational. I asked Meyer for a drill update.
“The drill feed developed problems retracting (two stabilizer prongs on either side of the drill retract, controlling the rate of drill penetration),” Meyer replied.
“Because the root cause has not been found (think FOD) and the concern about the situation getting worse, the drill feed has been retracted and the engineers are working on drilling without the stabilizing prongs.”
“Note, a consequence is that you can still drill and collect sample but a) there is added concern about getting the drill stuck and b) a new method of delivering sample needs to be developed and tested (the drill feed normally needs to be moved to move the sample into the chimera). One option that looks viable is reversing the drill – it does work and they are working on the scripts and how to control sample size.”
Ascending and diligently exploring the sedimentary lower layers of Mount Sharp, which towers 3.4 miles (5.5 kilometers) into the Martian sky, is the primary destination and goal of the rover’s long term scientific expedition on the Red Planet.
“Lower Mount Sharp was chosen as a destination for the Curiosity mission because the layers of the mountain offer exposures of rocks that record environmental conditions from different times in the early history of the Red Planet. Curiosity has found evidence for ancient wet environments that offered conditions favorable for microbial life, if Mars has ever hosted life,” says NASA.
Stay tuned. In part 2 we’ll discuss the key findings from Curiosity’s first 5 years exploring the Red Planet.
As of today, Sol 1850, Oct. 19, 2017, Curiosity has driven over 10.89 miles (17.53 kilometers) since its August 2012 landing inside Gale Crater from the landing site to the ridge, and taken over 445,000 amazing images.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
You can catch a glimpse of what its like to see NASA’s Curiosity Mars rover simultaneously high overhead from orbit and trundling down low across the Red Planet’s rocky surface as she climbs the breathtaking terrain of Mount Sharp – as seen in new images from NASA we have stitched together into a mosaic view showing the perspective views; see above.
Earlier this month on June 5, researchers commanded NASA’s Mars Reconnaissance Orbiter (MRO) to image the car sized Curiosity rover from Mars orbit using the spacecrafts onboard High Resolution Imaging Science Experiment (HiRISE) telescopic camera during Sol 1717 of her Martian expedition – see below.
HiRISE is the most powerful telescope ever sent to Mars.
And as she does nearly every Sol, or Martian day, Curiosity snapped a batch of new images captured from Mars surface using her navigation camera called navcam – likewise on Sol 1717.
Since NASA just released the high resolution MRO images of Curiosity from orbit, we assembled together the navcam camera raw images taken simultaneously on June 5 (Sol 1717), in order to show the actual vista seen by the six wheeled robot from a surface perspective on the same day.
The lead navcam photo mosaic shows a partial rover selfie backdropped by the distant rim of Gale Crater – and was stitched together by the imaging team of Ken Kremer and Marco Di Lorenzo.
Right now NASA’s Curiosity Mars Science Laboratory (MSL) rover is approaching her next science destination named “Vera Rubin Ridge” while climbing up the lower reaches of Mount Sharp, the humongous mountain that dominates the rover’s landing site inside Gale Crater.
“When the MRO image was taken, Curiosity was partway between its investigation of active sand dunes lower on Mount Sharp, and “Vera Rubin Ridge,” a destination uphill where the rover team intends to examine outcrops where hematite has been identified from Mars orbit,” says NASA.
“HiRISE has been imaging Curiosity about every three months, to monitor the surrounding features for changes such as dune migration or erosion.”
The MRO image has been color enhanced and shows Curiosity as a bright blue feature. It is currently traveling on the northwestern flank of Mount Sharp. Curiosity is approximately 10 feet long and 9 feet wide (3.0 meters by 2.8 meters).
“The exaggerated color, showing differences in Mars surface materials, makes Curiosity appear bluer than it really looks. This helps make differences in Mars surface materials apparent, but does not show natural color as seen by the human eye.”
See our mosaic of “Vera Rubin Ridge” and Mount Sharp below.
Curiosity is making rapid progress towards the hematite-bearing location of Vera Rubin Ridge after conducting in-depth exploration of the Bagnold Dunes earlier this year.
“Vera Rubin Ridge is a high-standing unit that runs parallel to and along the eastern side of the Bagnold Dunes,” says Mark Salvatore, an MSL Participating Scientist and a faculty member at Northern Arizona University, in a new mission update.
“From orbit, Vera Rubin Ridge has been shown to exhibit signatures of hematite, an oxidized iron phase whose presence can help us to better understand the environmental conditions present when this mineral assemblage formed.”
Curiosity will use her cameras and spectrometers to elucidate the origin and nature of Vera Rubin Ridge and potential implications or role in past habitable environments.
“The rover will turn its cameras to Vera Rubin Ridge for another suite of high resolution color images, which will help to characterize any observed layers, fractures, or geologic contacts. These observations will help the science team to determine how Vera Rubin Ridge formed and its relationship to the other geologic units found within Gale Crater.”
To reach Vera Rubin Ridge, Curiosity is driving east-northeast around two small patches of dunes just to the north. She will then turn “southeast and towards the location identified as the safest place for Curiosity to ascend the ridge. Currently, this ridge ascent point is approximately 370 meters away.”
Ascending and diligently exploring the sedimentary lower layers of Mount Sharp, which towers 3.4 miles (5.5 kilometers) into the Martian sky, is the primary destination and goal of the rovers long term scientific expedition on the Red Planet.
“Lower Mount Sharp was chosen as a destination for the Curiosity mission because the layers of the mountain offer exposures of rocks that record environmental conditions from different times in the early history of the Red Planet. Curiosity has found evidence for ancient wet environments that offered conditions favorable for microbial life, if Mars has ever hosted life,” says NASA.
As of today, Sol 1733, June 21, 2017, Curiosity has driven over 10.29 miles (16.57 kilometers) since its August 2012 landing inside Gale Crater, and taken over 420,000 amazing images.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
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Learn more about the upcoming SpaceX launch of BulgariaSat 1, recent SpaceX Dragon CRS-11 resupply launch to ISS, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
June 22-24: “SpaceX BulgariaSat 1 launch, SpaceX CRS-11 and CRS-10 resupply launches to the ISS, Inmarsat 5 and NRO Spysat, EchoStar 23, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity and Opportunity explore Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
Now well into her 13th year roving the Red Planet, NASA’s astoundingly resilient Opportunity rover has arrived at the precipice of “Perseverance Valley” – overlooking the upper end of an ancient fluid-carved valley on Mars “possibly water-cut” that flows down into the unimaginably vast eeriness of alien Endeavour crater.
Opportunity’s unprecedented goal ahead is to go ‘Where No Rover Has Gone Before!’
In a remarkable first time feat and treat for having ‘persevered’ so long on the inhospitably frigid Martian terrain, Opportunity has been tasked by her human handlers to drive down a Martian gully carved billions of years ago – by a fluid that might have been water – and conduct unparalleled scientific exploration, that will also extend into the interior of Endeavour Crater for the first time.
No Mars rover has done that before.
“This will be the first time we will acquire ground truth on a gully system that just might be formed by fluvial processes,” Ray Arvidson, Opportunity Deputy Principal Investigator of Washington University in St. Louis, told Universe Today.
“Opportunity has arrived at the head of Perseverance Valley, a possible water-cut valley here at a low spot along the rim of the 22-km diameter Endeavour impact crater,” says Larry Crumpler, a rover science team member from the New Mexico Museum of Natural History & Science.
NASA’s unbelievably long lived Martian robot reached a “spillway” at the top of “Perseverance Valley” in May after driving southwards for weeks from the prior science campaign at a crater rim segment called “Cape Tribulation.”
“The next month or so will be an exciting time, for no rover has ever driven down a potential ancient water-cut valley before,” Crumpler gushes.
“Perseverance Valley” is located along the eroded western rim of gigantic Endeavour crater – as illustrated by our exclusive photo mosaics herein created by the imaging team of Ken Kremer and Marco Di Lorenzo.
Read an Italian language version of this story here by Marco Di Lorenzo.
The mosaics show the “spillway” as the entry point to the ancient valley.
“Investigations in the coming weeks will “endeavor” to determine whether this valley was eroded by water or some other dry process like debris flows,” explains Crumpler.
“It certainly looks like a water cut valley. But looks aren’t good enough. We need additional evidence to test that idea.”
The valley slices downward from the crest line through the rim from west to east at a breathtaking slope of about 15 to 17 degrees – and measures about two football fields in length!
Huge Endeavour crater spans some 22 kilometers (14 miles) in diameter on the Red Planet. Perseverance Valley slices eastwards at approximately the 8 o’clock position of the circular shaped crater. It sits just north of a rim segment called “Cape Byron.”
Why go and explore the gully at Perseverance Valley?
“Opportunity will traverse to the head of the gully system [at Perseverance] and head downhill into one or more of the gullies to characterize the morphology and search for evidence of deposits,” Arvidson elaborated.
“Hopefully test among dry mass movements, debris flow, and fluvial processes for gully formation. The importance is that this will be the first time we will acquire ground truth on a gully system that just might be formed by fluvial processes. Will search for cross bedding, gravel beds, fining or coarsening upward sequences, etc., to test among hypotheses.”
Exploring the ancient valley is the main science destination of the current two-year extended mission (EM #10) for the teenaged robot, that officially began Oct. 1, 2016. It’s just the latest in a series of extensions going back to the end of Opportunity’s prime mission in April 2004.
What are the immediate tasks ahead that Opportunity must accomplish before descending down the gully to thoroughly and efficiently investigate the research objectives?
In a nutshell, extensive imaging from a local high point promontory to create a long-baseline 3 D stereo image of the valley and a “walk-about” to assess the local geology.
The rover is collecting images from two widely separated points at a dip at the valley spillway to build an “extraordinarily detailed three-dimensional analysis of the terrain” called a digital elevation map.
“Opportunity has been working on a panorama from the overlook for the past couple of sols. The idea is to get a good overview of the valley from a high point before driving down it,” Crumpler explains.
“But before we drive down the valley, we want to get a good sense of the geologic features here on the head of the valley. It could come in handy as we drive down the valley and may help us understand some things, particularly the lithology of any materials we find on the valley floor or at the terminus down near the crater floor.”
“So we will be doing a short “walk-about” here on the outside of the crater rim near the “spillway” into the valley.”
“We will drive down it to further assess its origin and to further explore the structure and stratigraphy of this large impact crater.”
The six wheeled rover landed on Mars on January 24, 2004 PST on the alien Martian plains at Meridiani Planum – as the second half of a stupendous sister act.
Expected to last just 3 months or 90 days, Opportunity has now endured nearly 13 ½ years or an unfathomable 53 times beyond the “warrantied” design lifetime.
Her twin sister Spirit, had successfully touched down 3 weeks earlier on January 3, 2004 inside 100-mile-wide Gusev crater and survived more than six years.
Opportunity has been exploring Endeavour almost six years – since arriving at the humongous crater in 2011. Endeavour crater was formed when it was carved out of the Red Planet by a huge meteor impact billions of years ago.
“Endeavour crater dates from the earliest Martian geologic history, a time when water was abundant and erosion was relatively rapid and somewhat Earth-like,” explains Crumpler.
Exactly what the geologic process was that carved Perseverance Valley into the rim of Endeavour Crater billions of years ago has not yet been determined, but there are a wide range of options researchers are considering.
“Among the possibilities: It might have been flowing water, or might have been a debris flow in which a small amount of water lubricated a turbulent mix of mud and boulders, or might have been an even drier process, such as wind erosion,” say NASA scientists.
“The mission’s main objective with Opportunity at this site is to assess which possibility is best supported by the evidence still in place.”
Extensive imaging with the mast mounted pancam and navcam cameras is currently in progress.
“The long-baseline stereo imaging will be used to generate a digital elevation map that will help the team carefully evaluate possible driving routes down the valley before starting the descent,” said Opportunity Project Manager John Callas of JPL, in a statement.
“Reversing course back uphill when partway down could be difficult, so finding a path with minimum obstacles will be important for driving Opportunity through the whole valley. Researchers intend to use the rover to examine textures and compositions at the top, throughout the length and at the bottom, as part of investigating the valley’s history.”
The team is also dealing with a new wheel issue and evaluating fixes. The left-front wheel is stuck due to an actuator stall.
“The rover experienced a left-front wheel steering actuator stall on Sol 4750 (June 4, 2017) leaving the wheel ‘toed-out’ by 33 degrees,” the team reported in a new update.
Thus the extensive Pancam panorama is humorously being called the “Sprained Ankle Panorama.” Selected high-value targets of the surrounding area will be imaged with the full 13-filter Pancam suite.
After reaching the bottom of Perseverance Valley, Opportunity will explore the craters interior for the first time during the mission.
“Once down at the end of the valley, Opportunity will be directed to explore the crater fill on a drive south at the foot of the crater walls,” states Crumpler.
As of today, June 17, 2017, long lived Opportunity has survived over 4763 Sols (or Martian days) roving the harsh environment of the Red Planet.
Opportunity has taken over 220,800 images and traversed over 27.87 miles (44.86 kilometers) – more than a marathon.
See our updated route map below. It shows the context of the rovers over 13 year long traverse spanning more than the 26 mile distance of a Marathon runners race.
The rover surpassed the 27 mile mark milestone on November 6, 2016 (Sol 4546).
As of Sol 4759 (June 13, 2017) the power output from solar array energy production is currently 343 watt-hours with an atmospheric opacity (Tau) of 0.842 and a solar array dust factor of 0.529, before heading into another southern hemisphere Martian winter later in 2017. It will count as Opportunity’s 8th winter on Mars.
“The science team is really jazzed at starting to see this area up close and looking for clues to help us distinguish among multiple hypotheses about how the valley formed,” said Opportunity Project Scientist Matt Golombek of NASA’s Jet Propulsion Laboratory, Pasadena, California.
Meanwhile Opportunity’s younger sister rover Curiosity traverses and drills into the lower sedimentary layers at the base of Mount Sharp.
And NASA continues building the next two robotic missions due to touch down in 2018 and 2020.
NASA as well is focusing its human spaceflight effort on sending humans on a ‘Journey to Mars’ in the 2030s with the Space Launch System (SLS) mega rocket and Orion deep space crew capsule.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
………….
Learn more about the Opportunity rover and upcoming SpaceX launch of BulgariaSat 1, recent SpaceX Dragon CRS-11 resupply launch to ISS, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
June 17-19: “Opportunity Mars rover, SpaceX BulgariaSat 1 launch, SpaceX CRS-11 and CRS-10 resupply launches to the ISS, Inmarsat 5 and NRO Spysat, EchoStar 23, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity explores Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
Following is the final excerpt from my new book, “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos.” The book is an inside look at several current NASA robotic missions, and this excerpt is part 3 of 3 posted here on Universe Today, of Chapter 2, “Roving Mars with Curiosity.” You can read Part 1 here, and Part 2 here. The book is available in print or e-book (Kindle or Nook) Amazon and Barnes & Noble.
How does Curiosity know where and how to drive across Mars’ surface? You might envision engineers at JPL using joysticks, similar to those used for remote control toys or video games. But unlike RC driving or gaming, the Mars rover drivers don’t have immediate visual inputs or a video screen to see where the rover is going. And just like at the landing, there is always a time delay of when a command is sent to the rover and when it is received on Mars.
“It’s not driving in a real-time interactive sense because of the time lag,” explained John Michael Morookian, who leads the team of rover drivers.
The actual job title of Morookian and his team are ‘Rover Planners,’ which precisely describes what they do. Instead of ‘driving’ the rovers per se; they plan out the route in advance, program specialized software, and upload the instructions to Curiosity.
“We use images taken by the rover of its surroundings,” said Morookian. “We have a set of stereo images from four black-and-white Navigation Cameras, along with images from the Hazcams (hazard avoidance cameras), supported by high-resolution color images from the MastCam that give us details about the nature of the terrain ahead and clues about types of rocks and minerals at the site. This helps identify structures that look interesting to the scientists.”
Using all available data, they can create a three-dimensional visualization of the terrain with specialized software called the Rover Sequencing and Visualization Program (RSVP).
“This is basically a Mars simulator and we put a simulated Curiosity in a panorama of the scene to visualize how the rover could traverse on its path,” Morookian explained. “We can also put on stereo glasses, which allow our eyes to see the scene in three dimensions as if we were there with the rover.
In virtual reality, the rover drivers can manipulate the scene and the rover to test every possibility of which routes are the best and what areas to avoid. There, they can make all the mistakes (get stuck in a dune, tip the rover, crash into a big rock, drive off a precipice) and perfect the driving sequence while the real rover remains safe on Mars.
“The scientists also review the images for features that are interesting and consult with the Rover Planners to help define a path. Then we compose the detailed commands that are necessary to get Curiosity from Point A to Point B along that path,” Morookian said. “”We can also incorporate the commands needed to give the rover direction to make contact with the site using its robotic arm.”
So, every night the rover is commanded to shut down for eight hours to recharge its batteries with the nuclear generator. But first Curiosity sends data to Earth, including pictures of the terrain and any science information. On Earth, the Rover Planners take that data, do their planning work, complete the software programing and beam the information back to Mars. Then Curiosity wakes up, downloads the instructions and sets to work. And the cycle repeats.
Curiosity also has an AutoNav feature which allows the rover to traverse areas the team hasn’t seen yet in images. So, it could go over the hill and down the other side to uncharted territory, with the AutoNav sensing potential hazards.
“We don’t use it too often because it is computationally expensive, meaning it takes much longer for the rover to operate in that mode,” Morookian said. “We often find it’s a better trade to just come in the next day, look at the images and drive as far as we can see.”
As Morookian showed me the various rooms used by rover planning teams at JPL, he explained how they need to operate over a number of different timescales.
“We not only have the daily route planning,” he said, “but also do long-range strategic planning using orbital imagery from the HiRISE camera on the Mars Reconnaissance Orbiter and choose paths based on features seen from orbit. Our team works strategically, looking many months out to define the best paths.”
Another process called Supra-Tactical looks out to just the next week. This involves science planners managing and refining the types of activities the rover will be doing in the short term. Also, since no one on the team lives on Mars Time anymore, on Fridays the Rover Planners work out the plans for several days.
“Since we don’t work weekends, Friday plans contain multiple sols of activities,” Morookian said. “Two parallel teams decide which days the rover will drive and which days it will do other activities, such as work with the robotic arm or other instruments.”
The data that comes down from the rover over the weekend is monitored, however, and if there is a problem, a team is called in to do a more detailed assessment. Morookian indicated they’ve had to engage the emergency weekend team several times, but so far there have been no serious problems. “It does keep us on our toes, however,” he said.
The rover features a number of reactive safety checks on the amount of overall tilt of the rover deck and the articulation of the suspension system of the wheels, so if the rover is going over an object that is too large, it will automatically stop.
Curiosity wasn’t built for speed. It was designed to travel up to 660 feet (200 meters) in a day, but it rarely travels that far in a Sol. By early 2016 the rover had driven a total of about 7.5 miles (12 km) across Mars’ surface.
There are several ways to determine how far Curiosity has traveled, but the most accurate measurement is called ‘Visual Odometry.’ Curiosity has specialized holes in its wheels in the shape of Morse code letters, spelling out ‘JPL’ – a nod to the home of the rover’s science and engineering teams – across the Martian soil.
“Visual odometry works by comparing the most recent pair of stereo images collected roughly every meter over the drive,” said Morookian. “Individual features in the scene are matched and tracked to provide a measure of how the camera (and thus the rover) has translated and rotated in 3 dimensional space between the two images and it tells us in a very real sense how far Curiosity has gone.”
Careful inspection of the rover tracks can reveal the type of traction the wheels have and if they have slipped, for instance due to high slopes or sandy ground.
Unfortunately, Curiosity now has new holes in its wheels that aren’t supposed to be there.
Morookian and Project Scientist Ashwin Vasavada both expressed relief and satisfaction that overall — this far into the mission — Curiosity is a fairly healthy rover. The entire science payload is currently operating at nearly full capability. But the engineering team keeps an eye on a few issues.
“Around sol 400, we realized the wheels were wearing faster than we expected,” Vasavada said.
And the wear didn’t consist of just little holes; the team started to see punctures and nasty tears. Engineers realized the holes were being created by the hard, jagged rocks the rover was driving over during that time.
“We weren’t fully expecting the kind of ‘pointy’ rocks that were doing damage,” Vasavada said. “We also did some testing and saw how one wheel could push another wheel into a rock, making the damage worse. We now drive more carefully and don’t drive as long as we have in the past. We’ve been able to level off the damage to a more acceptable rate.”
Early in the mission, Curiosity’s computer went into ‘safe mode’ several times, as Curiosity’s software recognized a problem, and the response was to disallow further activity and phone home.
Specialized fault protection software runs throughout the modules and instruments, and when a problem occurs, the rover stops and sends data called ‘event records’ to Earth. The records include various categories of urgency, and in early 2015, the rover sent a message that essentially said, “This is very, very bad.” The drill on the rover’s arm had experienced a fluctuation in an electrical current – like a short circuit.
“Curiosity’s software has the ability to detect shorts, like the ground fault circuit interrupter you have in your bathroom,” Morookian explained, “except this one tells you ‘this is very, very bad’ instead of just giving you a yellow light.”
Since the team can’t go to Mars and repair a problem, everything is fixed either by sending software updates to the rover or by changing operational procedures.
“We are just more careful now with how we use the drill,” Vasavada said, “and don’t drill with full force at the beginning, but slowly ramp up. It’s sort of like how we drive now, more gingerly but it still gets the job done. It hasn’t been a huge impact as of yet.”
A lighter touch on the drill also was necessary for the softer mudstones and sandstones the rover encountered. Morookian said there was concern the layered rocks might not hold up under the assault of the standard drilling protocol, and so they adjusted the technique to use the lowest ‘settings’ that still allows the drill to make sufficient progress into the rock.
But opportunities to use the drill are increasing as Curiosity begins its traverse up the mountain. The rover is traveling through what Vasavada calls a “target rich, very interesting area,” as the science team works to tie together the geological context of everything they are seeing in the images.
While the diversion at Yellowknife Bay allowed the team to make some major discoveries, they felt pressure to get to Mt. Sharp, so “drove like hell for a year,” Vasavada said.
Now on the mountain, there is still the pressure to make the most of the mission, with the goal of making it through at least four different rock units – or layers — on Mt. Sharp. Each layer could be like a chapter in the book of Mars’ history.
“Exploring Mt. Sharp is fascinating,” Vasavada said, “and we’re trying to maintain a mix between really great discoveries, which – you hate to say — slows us down, and getting higher on the mountain. Looking closely at a rock in front of you means you’ll never be able to go over and look at that other interesting rock over there.”
Vasavada and Morookian both said it’s a challenge to preserve that balance every day — to find what’s called the ‘knee in the curve’ or ‘sweet spot’ of the perfect optimization between driving and stopping for science.
Then there’s the balance between stopping to do a full observation with all the instruments and doing ‘flyby science’ where less intense observations are made.
“We take the observations we can, and generate all the hypotheses we can in real time,” Vasavada said. “Even if we’re left with 100 open questions, we know we can answer the questions later as long as we know we’ve taken enough data.”
Curiosity’s primary target is not the summit, but instead a region about 1,330 feet (400 meters) up where geologists expect to find the boundary between rocks that saw a lot of water in their history, and those that didn’t. That boundary will provide insight into Mars’ transition from a wet planet to dry, filling in a key gap in the understanding of the planet’s history.
No one really knows how long Curiosity will last, or if it will surprise everyone like its predecessors Spirit and Opportunity. Having made it past the ‘prime mission’ of one year on Mars (two Earth years), and now in the extended mission, the one big variable is the RTG power source. While the available power will start to steadily decrease, both Vasavada and Morookian don’t expect that to be in an issue for at least four more Earth years, and with the right “nurturing,” power could last for a dozen years or more.
But they also know there’s no way to predict how long Curiosity will go, or what unexpected event might end the mission.
Does Curiosity have a personality like the previous Mars rovers?
“Actually no, we don’t seem to anthropomorphize this rover like people did with Spirit and Opportunity,” Vasavada said. “We haven’t bonded emotionally with it. Sociologists have actually been studying this.” He shook his head with an amused smile.
Vasavada indicated it might have something to do with Curiosity’s size.
“I think of it as a giant beast,” he said straight-faced. “But not in a mean way at all.”
What has come to come to characterize this mission, Vasavada said, is the complexity of it, in every dimension: the human component of getting 500 people to work and cooperate together while optimizing everyone’s talents; keeping the rover safe and healthy; and keeping ten instruments going every day, which are sometimes doing completely unrelated science tasks.
“Every day is our own little ‘seven minutes of terror,’ where so many things have to go right every single day,” Vasavada said. “There are a million potential issues and interactions, and you have to constantly be thinking about all the ways things can go wrong, because there are a million ways you can mess up. It’s an intricate dance, but fortunately we have a great team.”
Then he added with a smile, “This mission is exciting though, even if it’s a beast.”
“Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” is published by Page Street Publishing, a subsidiary of Macmillan.
Following is Part 2 of an excerpt from my new book, “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos.” The book is an inside look at several current NASA robotic missions, and this excerpt is part 2 of 3 which will be posted here on Universe Today, of Chapter 2, “Roving Mars with Curiosity.” You can read Part 1 here. The book is available in print or e-book (Kindle or Nook) Amazon and Barnes & Noble.
The landing occurred at 10:30 pm in California. The MSL team had little time to celebrate, transitioning immediately to mission operations and planning the rover’s first day of activity. The team’s first planning meeting started at 1 o’clock in the morning, ending about 8 a.m. They had been up all night, putting in a nearly 40-hour day.
This was a rough beginning of the mission for the scientists and engineers who needed to live on ‘Mars Time.’
A day on Mars day is 40 minutes longer than Earth’s day, and for the first 90 Mars days – called sols — of the mission, the entire team worked in shifts around the clock to constantly monitor the newly landed rover. To operate on the same daily schedule as the rover meant a perpetually shifting sleep/wake cycle where the MSL team would alter their schedules 40 minutes every day to stay in sync with the day and night schedules on Mars. If team members came into work at 9:00 a.m., the next day, they’d come in at 9:40 a.m., and the next day at 10:20 a.m., and so on.
Those who have lived through Mars Time say their bodies continually feel jet-lagged. Some people slept at JPL so as not to disrupt their family’s schedule, some wore two watches so they would know what time it was on two planets.
About 350 scientists from around the world were involved with MSL and many of them stayed at JPL for the first 90 sols of the mission, living on Mars Time.
But it took less than 60 Earth days for the team to announce Curiosity’s first big discovery.
Ashwin Vasavada grew up in California and has fond childhood memories of visiting state and national parks in the southwest United States with his family, playing among sand dunes and hiking in the mountains. He’s now able to do both on another planet, vicariously through Curiosity. The day I visited Vasavada at his office at JPL in early 2016, the rover was navigating through a field of giant sand dunes at the base of Mount Sharp, with some dunes towering 30 feet (9 meters) above the rover.
“It’s just fascinating to see dunes close up on another planet,” Vasavada said. “And the closer we get to the mountain, the more fantastic the geology gets. So much has gone on there, and we have so little understanding of it … as of yet.”
At the time we talked, Curiosity was approaching four Earth years on Mars. The rover is now studying those enticing sedimentary layers on Mt. Sharp in closer detail. But first, it needed to navigate through the “Bagnold Dunes” which form a barrier along the northwestern flank of the mountain. Here, Curiosity is doing what Vasavada calls “flyby science,” stopping briefly to sample and study the sand grains of the dunes while moving through the area as quickly as possible.
Now working as the lead Project Scientist for the mission, Vasavada plays an even larger role in coordinating the mission.
“It’s a constant balance of doing things quickly, carefully and efficiently, as well as using the instruments to their fullest,” he said.
Since the successful August 2012 landing, Curiosity has sent back tens of thousands of images from Mars – from expansive panoramas to extreme close-ups of rocks and sand grains, all of which are helping to tell the story of Mars’ past.
The images the public seems to love the most are the ‘selfies,’ the photos the rover takes of itself sitting on Mars. The selfies aren’t just a single image like the ones we take with our cell phones, but a mosaic created from dozens of separate images taken with the Mars Hand Lens Imager (MAHLI) camera at the end of the rover’s robotic arm. Other fan favorites are the pictures Curiosity takes of the magnificent Martian landscape, like a tourist documenting its journey.
Vasavada has a unique personal favorite.
“For me, the most meaningful picture from Curiosity really isn’t that great of an image,” he said, “but it was one of our first discoveries so it has an emotional tie to it.”
Within the first 50 sols, Curiosity took pictures of what geologists call conglomerates: a rock made of pebbles cemented together. But these were no ordinary pebbles — they were pebbles worn by flowing water. Serendipitously, the rover had found an ancient streambed where water once flowed vigorously. From the size of pebbles, the science team could interpret the water was moving about 3 feet (1 meter) per second, with a depth somewhere between a few inches to several feet.
“When you see this picture, and whether you are a gardener or geologist, you know what this means,” Vasasvada said excitedly. “At Home Depot, the rounded rock for landscaping are called river pebbles! It was mind-blowing to me to think that the rover was driving through a streambed. That picture really brought home there was actually water flowing here long ago, probably ankle to hip deep.”
Vasavada looked down. “It still gives me the shivers, just thinking about it,” he said, with his passion for exploration and discovery visibly evident.
From that early discovery, Curiosity continued to find more water-related evidence. The team took a calculated gamble and instead of driving straight towards Mt. Sharp, took a slight detour to the east to an area dubbed ‘Yellowknife Bay.’
“Yellowknife Bay was something we saw with the orbiters,” Vasavada explained, “and there appeared to be a debris fan fed by a river—evidence for flowing water in the ancient past.”
Credits: NASA/JPL-Caltech/Univ. of Arizona
Here, Curiosity fulfilled ones of its main goals: determining whether Gale Crater ever was habitable for simple life forms. The answer was a resounding yes. The rover sampled two stone slabs with the drill, feeding half-baby-aspirin-sized portions to SAM, the onboard lab. SAM identified traces of elements like carbon, hydrogen, nitrogen, oxygen, and more —the basic building blocks of life. It also found sulfur compounds in different chemical forms, a possible energy source for microbes.
Data gathered by Curiosity’s other instruments constructed a portrait detailing how this site was once a muddy lakebed with mild – not acidic – water. Add in the essential elemental ingredients for life, and long ago, Yellowknife Bay would have been the perfect spot for living organisms to hang out. While this finding doesn’t necessarily mean there is past or present life on Mars, it shows the raw ingredients existed for life to get started there at one time, in a benign environment.
“Finding the habitable environment in Yellowknife Bay was wonderful because it really showed the capability our mission has to measure so many different things,” Vasavada said. “A wonderful picture came together of streams that flowed into a lake environment. This was exactly what we were sent there to find, but we didn’t think we’d find it that early in the mission.”
Still, this lakebed could have been created by a one-time event over just hundreds of years. The ‘jackpot’ would be to find evidence of long-term water and warmth.
That discovery took a little longer. But personally, it means more to Vasavada.
Mars’ climate was one of Vasavada’s early interests in his career and he spent years creating models, trying to understand Mars’ ancient history.
“I grew up with pictures of Mars from the Viking mission,” he said, “and thinking of it as a barren place with jagged volcanic rock and a bunch of sand. Then I had done all this theoretical work about Mars climate, that rivers and oceans perhaps once existed on Mars, but we had no real evidence.”
That’s why the discovery made by Curiosity in late 2015 is so exciting to Vasavada and his team.
“We didn’t just see the rounded pebbles and remnants of the muddy lake bottom at Yellowknife Bay, but all along the route,” Vasavada said. “We saw river pebbles first, then tilted sandstones where the river emptied into lakes. Then as we got to Mt. Sharp, we saw huge expanses of rock made of the silt that settled out from the lakes.”
The explanation that best fits the “morphology” in this region — that is, the configuration and evolution of rocks and land forms – is rivers formed deltas as they emptied into a lake. This likely occurred 3.8 to 3.3 billion years ago. And the rivers delivered sediment that slowly built up the lower layers of Mt. Sharp.
“My gosh, we were seeing this full system now,” Vasavada explained, “showing how the entire lower few hundred meters of Mount Sharp were likely laid down by these river and lake sediments. That means this event didn’t take hundreds or thousands of years; it required millions of years for lakes and rivers to be present to slowly build up, millimeter by millimeter, the bottom of the mountain.”
For that, Mars also needed a thicker atmosphere than it has now, and a greenhouse gas composition that Vasavada said they haven’t quite figured out yet.
But then, somehow dramatic climate change caused the water to disappear and winds in the crater carved the mountain to its current shape.
The rover had landed in exactly the right place, because here in one area was a record of much of Mars’ environmental history, including evidence of a major shift in the planet’s climate, when the water that once covered Gale Crater with sediment dried up.
“This all is a significant driver now for what we need to explain about Mars’ early climate,” Vasavada said. “You don’t get millions of years of climate change from a single event like a meteor hit. This discovery has broad implications for the entire planet, not just Gale Crater.”
• Silica: The rover made a completely unanticipated discovery of high-content silica rocks as it approached Mt. Sharp. “This means that the rest of the normal elements that form rocks were stripped away, or that a lot of extra silica was added somehow,” Vasavada said, “both of which are very interesting, and very different from rocks we had seen before. It’s such a multifaceted and curious discovery, we’re going to take a while figuring it out.”
• Methane on Mars: Methane is usually a sign of activity involving organic matter — even, potentially, of life. On Earth, about 90 percent of atmospheric methane is produced from the breakdown of organic matter. On Mars, methane has been detected by other missions and telescopes over the years, but it was tenuous – the readings seemed to come and go, and are hard to verify. In 2014, the Tunable Laser Spectrometer within the SAM instrument observed a ten-fold increase in methane over a two-month period. What caused the brief and sudden increase? Curiosity will continue to monitor readings of methane, and hopefully provide an answer to the decades-long debate.
• Radiation Risks for Human Explorers: Both during her trip to Mars and on the surface, Curiosity measured the high-energy radiation from the Sun and space that poses a risk astronauts. NASA will use data from the Radiation Assessment Detector (RAD) instrument Curiosity’s data to design future missions to be safe for human explorers.
Tomorrow: The conclusion of this chapter, including ‘How To Drive a Mars Rover, and ‘The Beast.’ Part 1 is available here.
“Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” is published by Page Street Publishing, a subsidiary of Macmillan.
Following is an excerpt from my new book, “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos,” which will be released tomorrow, Dec. 20, 2016. The book is an inside look at several current NASA robotic missions, and this excerpt is part 1 of 3 which will be posted here on Universe Today, of Chapter 2, “Roving Mars with Curiosity.” The book is available for order on Amazon and Barnes & Noble.
It takes approximately seven minutes for a moderate-sized spacecraft – such as a rover or a robotic lander — to descend through the atmosphere of Mars and reach the planet’s surface. During those short minutes, the spacecraft has to decelerate from its blazing incoming speed of about 13,000 mph (20,900 kph) to touch down at just 2 mph (3 kph) or less.
This requires a Rube Goldberg-like series of events to take place in perfect sequence, with precise choreography and timing. And it all needs to happen automatically via computer, with no input from anyone on Earth. There is no way to guide the spacecraft remotely from our planet, about 150 million miles (250 million km) away. At that distance, the radio signal delay time from Earth to Mars takes over 13 minutes. Therefore, by the time the seven-minute descent is finished, all those events have happened – or not happened – and no one on Earth knows which. Either your spacecraft sits magnificently on the surface of Mars or lies in a crashed heap.
That’s why scientists and engineers from the missions to Mars call it “Seven Minutes of Terror.”
And with the Mars Science Laboratory (MSL) mission, which launched from Earth in November of 2011, the fear and trepidation about what is officially called the ‘Entry, Descent and Landing’ (EDL) increased exponentially. MSL features a 1-ton (900 kg), 6-wheeled rover named Curiosity, and this rover was going to use a brand new, untried landing system.
To date, all Mars landers and rovers have used — in order — a rocket-guided entry, a heat shield to protect and slow the vehicle, then a parachute, followed by thrusters to slow the vehicle even more. Curiosity would use this sequence as well. However, a final, crucial component encompassed one of the most complex landing devices ever flown.
Dubbed the “Sky Crane,” a hovering rocket stage would lower the rover on 66 ft. (20 meter) cables of Vectran rope like a rappelling mountaineer, with the rover soft-landing directly on its wheels. This all needed to be completed in a matter of seconds, and when the on-board computer sensed touchdown, pyrotechnics would sever the ropes, and the hovering descent stage would zoom away at full throttle to crash-land far from Curiosity.
Complicating matters even further, this rover was going to attempt the most precise off-world landing ever, setting down inside a crater next to a mountain the height of Mount Rainier.
A major part of the uncertainty was that engineers could never test the entire landing system all together, in sequence. And nothing could simulate the brutal atmospheric conditions and lighter gravity present on Mars except being on Mars itself. Since the real landing would be the first time the full-up Sky Crane would be used, there were questions: What if the cables didn’t separate? What if the descent stage kept descending right on top of the rover?
If the Sky Crane didn’t work, it would be game-over for a mission that had already overcome so much: technical problems, delays, cost overruns, and the wrath of critics who said this $2.5 billion Mars rover was bleeding money away from the rest of NASA’s planetary exploration program.
With its red glow in the nighttime sky, Mars has beckoned skywatchers for centuries. As the closest planet to Earth that offers any potential for future human missions or colonization, it has been of great interest in the age of space exploration. To date, over 40 robotic missions have been launched to the Red Planet … or more precisely, 40-plus missions have been attempted.
Including all US, European, Soviet/Russian and Japanese efforts, more than half of Mars missions have failed, either because of a launch disaster, a malfunction en route to Mars, a botched attempt to slip into orbit, or a catastrophic landing. While recent missions have had greater success than our first pioneering attempts to explore Mars in situ (on location) space scientists and engineers are only partially kidding when they talk about things like a ‘Great Galactic Ghoul’ or the ‘Mars Curse’ messing up the missions.
But there have been wonderful successes, too. Early missions in the 1960’s and 70’s such as Mariner orbiters and Viking landers showed us a strikingly beautiful, although barren and rocky world, thereby dashing any hopes of ‘little green men’ as our planetary neighbors. But later missions revealed a dichotomy: magnificent desolation combined with tantalizing hints of past — or perhaps even present day – water and global activity.
Today, Mars’ surface is cold and dry, and its whisper-thin atmosphere doesn’t shield the planet from bombardment of radiation from the Sun. But indications are the conditions on Mars weren’t always this way. Visible from orbit are channels and intricate valley systems that appear to have been carved by flowing water.
For decades, planetary scientists have debated whether these features formed during brief, wet periods caused by cataclysmic events such as a massive asteroid strike or sudden climate calamity, or if they formed over millions of years when Mars may have been continuously warm and wet. Much of the evidence so far is ambiguous; these features could have formed either way. But billions of years ago, if there were rivers and oceans, just like on Earth, life might have taken hold.
The Curiosity rover is the fourth mobile spacecraft NASA has sent to Mars’ surface. The first was a 23-pound (10.6 kg) rover named Sojourner that landed on a rock-covered Martian plain on July 4, 1997. About the size of a microwave oven, the 2-foot- (65 cm) long Sojourner never traversed more than 40 feet away from its lander and base station. The rover and lander together constituted the Pathfinder mission, which was expected to last about a week. Instead, it lasted nearly three months and the duo returned 2.6 gigabits of data, snapping more than 16,500 images from the lander and 550 images from the rover, as well as taking chemical measurements of rocks and soil and studying Mars’ atmosphere and weather. It identified traces of a warmer, wetter past for Mars.
The mission took place when the Internet was just gaining popularity, and NASA decided to post pictures from the rover online as soon as they were beamed to Earth. This ended up being one of the biggest events in the young Internet’s history, with NASA’s website (and mirror sites set up for the high demand) receiving over 430 million hits in the first 20 days after landing.
Pathfinder, too, utilized an unusual landing system. Instead of using thrusters to touch down on the surface, engineers concocted a system of giant airbags to surround and protect the spacecraft. After using the conventional system of a rocket-guided entry, heat shield, parachutes and thrusters, the airbags inflated and the cocooned lander was dropped from 100 feet (30 m) above the ground. Bouncing several times across Mars’ surface times like a giant beach ball, Pathfinder eventually came to a stop, the airbags deflated and the lander opened up to allow the rover to emerge.
While that may sound like a crazy landing strategy, it worked so well that NASA decided to use larger versions of the airbags for the next rover mission: two identical rovers named Spirit and Opportunity. The Mars Exploration Rovers (MER) are about the size of a riding lawn mower, at 5.2 feet (1.6 meters) long, weighing about 400 lbs (185 kilograms). Spirit landed successfully near Mars’ equator on January 4, 2004, and three weeks later Opportunity bounced down on the other side of the planet. The goal of MER was to find evidence of past water on Mars, and both rovers hit the jackpot. Among many findings, Opportunity found ancient rock outcrops that were formed in flowing water and Spirit found unusual cauliflower-shaped silica rocks that scientists are still studying, but they may provide clues to potential ancient Martian life.
Somehow, the rovers each developed a distinct ‘personality’ – or, perhaps a better way to phrase it is that people assigned personalities to the robots. Spirit was a problem child and drama queen but had to struggle for every discovery; Opportunity, a privileged younger sister, and star performer, as new findings seemed to come easy for her. Spirit and Opportunity weren’t designed to be adorable, but the charming rovers captured the imaginations of children and seasoned space veterans alike. MER project manager John Callas once called the twin rovers “the cutest darn things out in the Solar System.” As the long-lived, plucky rovers overcame hazards and perils, they sent postcards from Mars every day. And Earthlings loved them for it.
While it’s long been on our space to-do list, we haven’t quite yet figured out how to send humans to Mars. We need bigger and more advanced rockets and spacecraft, better technology for things like life support and growing our own food, and we really don’t have the ability to land the very large payloads needed to create a human settlement on Mars.
But in the meantime – while we try to figure all that out — we have sent the robotic equivalent of a human geologist to the Red Planet. The car-sized Curiosity rover is armed with an array of seventeen cameras, a drill, a scoop, a hand lens, and even a laser. These tools resemble equipment geologists use to study rocks and minerals on Earth. Additionally, this rover mimics human activity by mountain climbing, eating (figuratively speaking), flexing its (robotic) arm, and taking selfies.
This roving robotic geologist is also a mobile chemistry lab. A total of ten instruments on the rover help search for organic carbon that might indicate the raw material required by life, and “sniff” the Martian air, trying to smell if gasses like methane — which could be a sign of life — are present. Curiosity’s robotic arm carries a Swiss Army knife of gadgets: a magnifying lens-like camera, a spectrometer to measure chemical elements, and a drill to bore inside rocks and feed samples to the laboratories named SAM (Sample Analysis at Mars) and) and CheMin (Chemistry and Mineralogy). The ChemCam laser can vaporize rock from up to 23 feet (7 meters) away, and identify the minerals from the spectrum of light emitted from the blasted rock. A weather station and radiation monitor round out the devices on board.
With these cameras and instruments, the rover becomes the eyes and hands for an international team of about 500 earthbound scientists.
While the previous Mars rovers used solar arrays to gather sunlight for power, Curiosity uses an RTG like New Horizons. The electricity generated from the RTG repeatedly powers rechargeable lithium-ion batteries, and the RTG’s heat is also piped into the rover chassis to keep the interior electronics warm.
With Curiosity’s size and weight, the airbag landing system used by the previous rovers was out of the question. As NASA engineer Rob Manning explained, “You can’t bounce something that big.” The Sky Crane is an audacious solution.
Curiosity’s mission: figure out how Mars evolved over billions of years and determine if it once was — or even now is — capable of supporting microbial life.
Curiosity’s target for exploration: a 3.4 mile (5.5 km) -high Mars mountain scientists call Mt. Sharp (formally known as Aeolis Mons) that sits in the middle of Gale Crater, a 96-mile (155-km) diameter impact basin.
Gale was chosen from 60 candidate sites. Data from orbiting spacecraft determined the mountain has dozens of layers of sedimentary rock, perhaps built over millions of years. These layers could tell the story of Mars’ geologic and climate history. Additionally, both the mountain and the crater appear to have channels and other features that look like they were carved by flowing water.
The plan: MSL would land in a lower, flatter part of the crater and carefully work its way upward towards the mountain, studying each layer, essentially taking a tour of the epochs of Mars’ geologic history.
The hardest part would be getting there. And the MSL team only had one chance to get it right.
Curiosity’s landing on August 5, 2012 was one of the most anticipated space exploration events in recent history. Millions of people watched events unfold online and on TV, with social media feeds buzzing with updates. NASA TV’s feed from JPL’s mission control was broadcast live on the screens in New York’s Time Square and at venues around the world hosting ‘landing parties.’
But the epicenter of action was at JPL, where hundreds of engineers, scientists and NASA officials gathered at JPL’s Space Flight Operations Facility. The EDL team – all wearing matching light blue polo shirts — monitored computer consoles at mission control.
Two members of the team stood out: EDL team lead Adam Steltzner — who wears his hair in an Elvis-like pompadour — paced back and forth between the rows of consoles. Flight Director Bobak Ferdowski sported and an elaborate stars and stripes Mohawk. Obviously, in the twenty-first century, exotic hairdos have replaced the 1960’s black glasses and pocket protectors for NASA engineers.
At the time of the landing, Ashwin Vasavada was one of the longest serving scientists on the mission team, having joined MSL as the Deputy Project Scientist in 2004 when the rover was under construction. Back then, a big part of Vasavada’s job was working with the instrument teams to finalize the objectives of their instruments, and supervise technical teams to help develop the instruments and integrate them with the rover.
Each of the ten selected instruments brought a team of scientists, so with engineers, additional staff and students, there were hundreds of people getting the rover ready for launch. Vasavada helped coordinate every decision and modification that might affect the eventual science done on Mars. During the landing, however, all he could do was watch.
“I was in the room next door to the control room that was being shown on TV,” Vasavada said. “For the landing there was nothing I could do except realize the past eight years of my life and my entire future was all riding on that seven minutes of EDL.”
Plus, the fact that no would know the real fate of the rover until 13 minutes after the fact due to the radio delay time led to a feeling of helplessness for everyone at JPL.
“Although I was sitting in a chair,” Vasavada added, “I think I was mentally curled up in the fetal position.”
As Curiosity sped closer to Mars, three other veteran spacecraft already orbiting the planet moved into position to be able to keep an eye on the newcomer MSL as it transmitted information on its status. At first, MSL communicated directly to the Deep Space Network (DSN) antennas on Earth.
To make telemetry from the spacecraft as streamlined as possible during EDL, Curiosity sent out 128 simple but distinct tones indicating when steps in the landing process were activated. Allen Chen, an engineer in the control room announced each as they came: one sound indicated the spacecraft entered Mars’ atmosphere; another signaled the thrusters fired, guiding the spacecraft towards Gale Crater. Tentative clapping and smiles came from the team at Mission Control at the early tones, with emotions increasing as the spacecraft moved closer and closer to the surface.
Partway through the descent, MSL went below the Martian horizon, putting it out of communication with Earth. But the three orbiters — Mars Odyssey, Mars Reconnaissance Orbiter and Mars Express — were ready to capture, record and relay data to the DSN.
Seamlessly, the tones kept coming to Earth as each step of the landing continued flawlessly. The parachute deployed. The heat shield dropped away. A tone signaled the descent stage carrying the rover let go of the parachute, another indicated powered flight and descent toward the surface. Another tone meant the Sky Crane began lowering the rover to the surface.
A tone arrived, indicating Curiosity’s wheels touched the surface, but even that didn’t mean success. The team had to make sure the Sky Crane flyaway maneuver worked.
Then, came the tone they were waiting for: “Touchdown confirmed,” cheered Chen. “We’re safe on Mars!”
Pandemonium and joy erupted in JPL’s mission control, at the landing party sites, and on social media. It seemed the world celebrated together at that moment. Cost overruns, delays, all the negative things ever said about the MSL mission seemed to vanish with the triumph of landing.
“Welcome to Mars!” the Director of the Jet Propulsion Laboratory, Charles Elachi said at a press conference following the dramatic touchdown, “Tonight we landed, tomorrow we start exploring Mars. Our Curiosity has no limits.”
“The seven minutes actually went really fast,” said Vasavada. “It was over before we knew it. Then everybody was jumping up and down, even though most of us were still processing that it went so successfully.”
That the landing went so well — indeed perfectly — may have actually shocked some of the team at JPL. While they had rehearsed Curiosity’s landing several times, remarkably, they were never able to land the vehicle in their simulations.
“We tried to rehearse it very accurately,” Vasavada said, “so that everything was in synch — both the telemetry that we had simulated that would be coming from the spacecraft, along with real-time animations that had been created. It was a pretty complex thing, but it never actually worked. So the real, actual landing was the first time everything worked right.”
Curiosity was programmed to immediately take pictures of its surroundings. Within two minutes of the landing, the first images were beamed to Earth and popped up on the viewing screens at JPL.
“We had timed the orbiters to fly over during the landing, but didn’t know for sure if their relay link would last long enough to get the initial pictures down,” Vasavada said. “Those first pictures were fairly ratty because the protective covers were still on the cameras and the thrusters had kicked up a lot of dust on the covers. We couldn’t really see it very well but we still jumped up and down nevertheless because these were pictures from Mars.”
Amazingly, one of the first pictures showed exactly what the rover had been sent to study.
“We had landed with the cameras basically facing directly at Mt. Sharp,” Vasavada said, shaking his head. “In the HazCam (hazard camera) image, right between the wheels, we had this gorgeous shot. There was the mountain. It was like a preview of the whole mission, right in front of us.”
Tomorrow: Part 2 of “Roving Mars With Curiosity,” with ‘Living on Mars Time’ and ‘Discoveries’
“Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” is published by Page Street Publishing, a subsidiary of Macmillan.